This dissertation was written as part of the MSc in Strategic Product Design at
the International Hellenic University.
The 3d printing technology mainly used for rapid prototyping is a revolutionary
technology over the last years. 3d printing, also referred to as Additive Manufacturing
(AM), is a process of fabricating polymer, metallic, ceramic materials with complex
geometries. There have been several attempts to address the poor mechanical
characteristics of 3D printed parts. One option is to add fiber reinforcement to increase
structural strength. The composite's reinforcement might be either continuous or
discontinuous short fibers. The mechanical performance of discontinuous fiber is lower
than that of continuous fiber [1]. In this scenario, continuous carbon fiber with ultrahigh mechanical features is chosen.
In this study, samples from nylon and carbon fibers were printed using
Markforged Two printer through Continuous fiber fabrication. The effect of fiber volume
fraction, fiber orientation, and fiber distribution and placement on the flexural
properties were investigated using three-point flexural testing. The flexural mechanical
characteristics of composites are crucial factors to evaluate in structural applications.
The study aims to discover the best combination of fiber distribution and orientation
with as few reliable experiments as possible that have better mechanical properties in
bending.
The present study is prepared as follows. First is provided a brief overview of
published review articles focused on flexural test in 3d printing composite samples
(nylon or onyx with carbon fiber) and a comparison of mechanical properties. Next, the
Markforged 3d printer was presented, and analyzed the experimental methodology of
3d printing and flexural tests. Finally, the experimental results are evaluated and key
results are highlighted concerning the effect of different process parameters. According
to a literature review [2], flexural tests demonstrate that concentric pattern performs
better in bending than in tension. Therefore, saving time and carbon fiber material
specimens were printed specimens in top-bottom, central, and sandwich deposition
patterns with fibers oriented concentrically with 2 rings (concentric pattern). I focus on
iv
categories with better mechanical properties to change the orientation and fiber fill type
(for concentric to isotropic and hybrid). Conclusions and suggestions for future research
of this work are outlined.
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